The present invention relates to flame retardant organopolysiloxane-polycarbonate graft copolymers which can be made by effecting a platinum catalyzed addition between a silicon hydride organosiloxane and a bisphenol having at least one aliphatically unsaturated organic radical attached to the aromatic ring by a carbon-carbon bond. The aforementioned bisphenol organic-siloxane adduct can be phosgenated in combination with additional bisphenol to produce an organopolysiloxane-polycarbonate graft copolymer. An alternative procedure for making the flame retardant organopolysiloxane-polycarbonate graft copolymers is to effect the platinum catalyzed addition between a silicon hydride organosiloxane and an aromatic polycarbonate having a significant degree of aromatic ring substitution with C-C bound aliphatically unsaturated organic radicals.
In copending application Ser. No. 07/455,122, filed Dec. 12, 1989, flame retardant thermoplastic silicone polyphenylene ether graft copolymers are shown. A phenol-siloxane macromer is oxidatively coupled with monohydric phenol to produce a thermoplastic flame retardant silicone-polyphenylene ether graft copolymer. The phenolsiloxane macromer can be made by effecting a hydrosilylation addition reaction between an aliphatically unsaturated phenol and a hydride terminated polydiorganosiloxane.
Additional flame retardant aromatic thermoplastic organic polymers and methods for making are constantly being sought by the thermoplastics industry.
As used hereinafter, the term "flame retardance" or "nonflammable" with respect to the flame retardant polycarbonate compositions of the present invention means that the flame retardant polycarbonates have satisfied UL94 V-0 requirements for flammability, as shown by the "Flammability of Plastic Materials Bulletin" of Jan. 24, 1980. More particularly, a 5".times.1/2".times.1/8" polycarbonate test bar is suspended vertically over a 3/4" Bunsen Burner flame as provided in the aforementioned UL94 test. The test sample preferably exhibits a UL94 V-0 rating which includes the following criteria:
A. not have any specimens which burn with flaming combustion for more than 10 seconds after application of the test flame. PA1 B. not have a total flaming combustion time exceeding 50 seconds for 10 flame applications for each set of five specimens. PA1 C. not have any specimens which burn with flaming or glowing combustion up to the holding clamp. PA1 D. not have any specimens which drip flaming particles that ignite dry absorbent surgical cotton located 12 inches (305 mm) below the test specimen. PA1 E. not have any specimens with glowing combustion which persists for more than 30 seconds after the second removal of the test flame.